JPH04221966A - Copying machine provided with noise eliminating device - Google Patents

Abstract

PURPOSE:To make a noise low in the case of operation by an operator. CONSTITUTION:A sound wave or vibration generated inside a copying machine, which is the cause of the noise, is observed by noise source signal observation means 21 and 22 and converted to an electrical signal. The signal from the noise source signal observing means 21 and 22 is processed by a signal processing means 23 and converted to the sound wave by a speaker 24 and radiated to the vicinity of the head part of the operator at a copying machine operating position. The signal processing by the means 23 is previously decided so that the noise may be eliminated in the vicinity of the head part of the operator at the copying machine operating position by a signal processing adaptation means 32.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copying machine equipped with a noise reduction device capable of reducing noise to an operator.

0002

2. Description of the Related Art Copying machines generate noise in the surrounding area due to resonance caused by the rotation of a motor that is a driving source, and noise generated from paper and rollers during paper feeding. Therefore, conventionally, soundproofing measures have been taken in copying machines using sound absorbing materials, sound insulating materials, vibration damping materials, and the like. Also, JP-A-6
Japanese Patent Application No. 1-262166 describes a silencer for erasing the printing sound of an impact printer.

0003

[Problem to be solved by the invention] The above-mentioned copying machine uses a sound absorbing material,
Soundproofing measures are taken using sound insulating materials, vibration damping materials, etc.
Complete sound insulation was difficult due to space constraints inside the machine, paper entrances and exits, and openings for heat radiation. In particular, since the structure requires a paper entrance/exit, noise leaking outside from this paper entrance/exit has become a major problem unique to copying machines. Furthermore, since the operator is required to operate the copying machine close to the copying machine, the noise becomes loud at the operator's position while the copying machine is being operated, and the operator feels uncomfortable when operating the copying machine. Therefore, it has been a challenge to reduce the noise so that the operator does not feel so much noise during operation. The noise reduction device described in Japanese Patent Application Laid-Open No. 61-262166 is intended to eliminate the printing sound of an impact printer, but not the noise of a copying machine. The present invention improves the above drawbacks,
An object of the present invention is to provide a copying machine with a noise removal device capable of reducing noise.

0004

[Means for Solving the Problems] In order to achieve the above object, the invention of claim 1 provides noise source signal observation in which sound waves or vibrations generated inside a copying machine and causing noise are observed and converted into electrical signals. means, a signal processing means for processing the signal from the noise source signal observation means, a speaker for converting the signal from the signal processing means into a sound wave and emitting it near the operator's head at the copying machine operating position; and signal processing adaptation means for predetermining the signal processing of the processing means so that the area near the operator's head at the operating position of the copying machine is muted.

[0005]

According to the first aspect of the invention, the sound waves or vibrations generated inside the copying machine and causing noise are observed by the noise source signal observation means and converted into electrical signals. The signal from the noise source signal observation means is processed by the signal processing means, converted into a sound wave by a speaker, and radiated to the vicinity of the operator's head at the copying machine operating position. The signal processing of the signal processing means is determined in advance by the signal processing adaptation means so that the area near the operator's head at the copying machine operating position is muted.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a first embodiment of the present invention. This first embodiment is an example in which the present invention is applied to an electrophotographic copying machine. During a copying operation, the photosensitive drum 11 is rotationally driven by a main motor 12 and uniformly charged by a charger (not shown), and then the original image is exposed by an exposure device to form an electrostatic latent image. This electrostatic latent image is transferred to the developing device 13.
The image is developed into a visible image, and the transfer paper is fed from the paper feeding device 14 to the registration rollers 15. This transfer paper is sent out by the registration roller 15 with its leading edge aligned with the developed image on the photoreceptor drum 11, the developed image on the photoreceptor drum 11 is transferred by the transfer device 16, and the paper is transported by the paper transport section 17 to the fixing section. After the developed image is fixed by 18, it is discharged from a paper discharge port 19 onto a paper discharge tray 20 as a copy.

[0007] Due to its structure, a copying machine has openings for heat radiation such as an entrance and exit for transfer paper and a heat radiation fan, and these openings often radiate noise to the surroundings. Therefore, a noise source signal observation microphone 21 is attached to an opening for feeding and discharging paper or an opening for heat dissipation by a heat dissipation fan, for example, near the paper output port 20. Observe it as a noise source signal and convert it into an electrical signal. In addition, since vibrations of motors, etc. are cited as a cause of noise, vibrations of motors, etc. are observed with a vibration pickup, for example, the main motor 12.
The vibration is observed by a vibration pickup 22 and converted into an electrical signal. Both the noise source signal observation microphone 21 and the vibration pickup 22 may be provided, but only one of them may be provided. The noise source signals from the noise source signal observation microphone 21 and the vibration pickup 22 undergo appropriate signal processing in the signal processing circuit 23, are converted into sound waves by the speaker 24, and are output. The speaker 24 is installed on the front surface of the copying machine or on the operation panel so as to radiate sound waves toward the vicinity of the head of the operator at the copying machine operating position.

The signal processing circuit 31 is configured using a digital filter as shown in FIG.
A/D conversion is performed by a digital (A/D) converter 26. The output signal of this A/D converter 26 is transmitted to the digital filter 2.
7, is D/A converted by a digital/analog (D/A) converter 28, passes through an LPF 29, is amplified by a power amplifier 30, and is then converted into a sound wave by a speaker 24. At this time, it is necessary to design the coefficients of the digital filter 27 so that the noise generated inside the copying machine and transmitted to the vicinity of the operator's head and the control sound from the speaker 24 cancel each other out. This digital filter 27
The determination of the coefficients is performed by the signal processing adaptation means 32 (see FIG. 3). This signal processing adaptation means 32 is used to determine the signal processing of the signal processing circuit 23 when the operator is not performing a copying operation, such as when installing the copying machine or turning on the power.

[0009] Taking advantage of the fact that the operator's position when operating the copying machine does not change significantly, the operator can operate the copying machine as shown in FIG. 3 when installing the copying machine or turning on the power. One or more microphones 31 are placed there assuming the head position when
Set up. One or more of the noise source signal observation microphone 21 and the vibration pickup 22 may be provided, or both may be provided. For example, in the second embodiment of the present invention, in the first embodiment, As shown in Figure 4, two noise source signal observation microphones 2
1a and 21b are installed, two microphones 31a and 31b are installed near the operator's head, and a speaker 2
4 also has two speakers 24a and 24b installed between the noise source signal observation microphone 21a and the speaker 24a, an LPF 25a, an A/D converter 26a, a digital filter 27a, a D/A converter 28a, an LPF 29a, and a power A signal processing circuit 23a consisting of an amplifier 30a is provided, and an LPF 25b and an A/D converter 26b are provided between the noise source signal observation microphone 21b and the speaker 24b.
, digital filter 27b, D/A converter 28b, LP
Signal processing circuit 2 consisting of F29b and power amplifier 30b
3b is provided.

In this second embodiment, the noise Z1 at the installation position of the noise source signal observation microphone 21a is observed by the noise source signal observation microphone 21a, and the LP
The signal is transmitted through the F25a and the A/D converter 26a with a transfer function A1, and passes through the digital filter 27a with a transfer function W1. The output signal of this digital filter 27a is transmitted through a D/A converter 28a and an LPF 29a using a transfer function B1, amplified by a power amplifier 30a, and then sent to a speaker 24a.
is converted into a sound wave, and this sound wave transfers the external world with a transfer function D1
1 and is transmitted to the microphone 31a, and the external world is transmitted by a transfer function D21 to the microphone 31a.
1b. Similarly, the noise Z2 at the installation position of the noise source signal observation microphone 21b is observed by the noise source signal observation microphone 21b, and the noise Z2 is observed by the noise source signal observation microphone 21b.
, A/D converter 26b with transfer function A2, and passes through digital filter 27b with transfer function W2. The output signal of this digital filter 27b is sent to a D/A converter 28b.
, is transmitted through the LPF 29b using the transfer function B2, is amplified by the power amplifier 30b, and then converted into a sound wave by the speaker 24b.This sound wave is transmitted through the external world using the transfer function D12 and transmitted to the microphone 31a. D22 and transmitted to the microphone 31b. Furthermore, a noise source signal observation microphone 21
The noise Z1 at the installation position a transfers the external world to the transfer function G11
is transmitted to the microphone 31a, and the external world is transmitted by the transfer function G21 to the microphone 31a.
The noise Z2 at the installation position of the noise source signal observation microphone 21b is transmitted to the microphone 31a through the external world using a transfer function G12, and is transmitted through the external world using a transfer function G22 to the microphone 31b. Ru.

[0011] Therefore, digital filter j (27a
, 27b) to microphone i (31a, 31b) is Cij (i, j=1, 2), then Ci
j=Dij・Bj, and the output signal Ei (E1, E2) of microphone i (31a, 31b) is
) is the noise transmitted from the outside world to Pi, microphone i (
31a, 31b) from the speakers 24a, 24b, Ei=Pi+Si Pi=Gi1・Z1+Gi2・Z2 Si=Di1・B1・W1・A1・Z1+Di2・B2
・W2・A2・Z2. Therefore, W1 and W2 are adjusted to each signal processing adaptation means 3 so that Ei (E1, E2) approaches zero as much as possible.
2a and 32b, the noise near the operator's head will be reduced. Similarly, in the first embodiment, if the signal processing adaptation means 32 determines the coefficients of the digital filter 27 so that the output signal of the microphone 31 approaches zero as much as possible, noise near the operator's head can be reduced. become.

Next, regarding the signal processing adaptation means 32,
This will be explained using a coefficient determination method using the filtered-X LMS method. In the first embodiment, the transfer function C from the output of the digital filter 27 to the output of the microphone 31 via the speaker 24 and the outside world is measured. For this purpose, white noise is generated from the signal processing circuit 23,
The measurement may be performed using a well-known technique such as the LMS method or the cross-spectral method. Then, the copying machine is brought into operation to generate noise, and the following processing is performed while the noise is being generated. The output signal e(n) of the microphone 31 located near the operator's head at time n is A/
If the output signal of the D converter 26 is x(n), the transfer function from the output of the digital filter 27 to the microphone 31 is c, and s(n)=Σwi(n)·x(n-1),
e(n)=y(n)+Σcj・s(n-j)...
(1) becomes. In order to create a digital filter 27 with an appropriate coefficient w, the squared error E(n)={e
(n)}2 is updated by the signal processing adaptation means 32 for each sample. fil
The tered-X LMS algorithm, when E(n) is viewed as a quadratic equation with respect to wi, wi This is a method of updating each time. In this case, the coefficient wi(n+1) of the digital filter 27 at time (n+1) is
wi(n+1)=wi(n)+Δwi(n
)...(3) However, Δw1(n)=α
・e(n)・Σcj・x(n-i-j)
α: Given by convergence coefficient.

When the processing of the signal processing circuit 23 is determined as described above, the microphone 31 near the operator's head is removed during normal use, and the digital filter 27 is
The signal processing circuit 23 performs processing with the coefficient W of . By doing this, it is possible to use the microphone 31 during operation.
signal processing circuit 2 without placing it near the operator's head.
In addition, since the operator's position does not change much during operation of the copying machine, a sound deadening zone is always provided near the operator's head. Furthermore, in the second embodiment, the coefficients of the digital filters in each signal processing circuit are determined and fixed in the same way, so that the signal processing circuit can perform processing without placing a microphone near the operator's head. This means that there is always a sound deadening zone near the operator's head.

[0014]

As described above, according to the present invention of claim 1, there is provided a noise source signal observation means for observing sound waves or vibrations generated inside a copying machine and causing noise, and converting the observed sound waves or vibrations into electrical signals; a signal processing means for processing the signal from the noise source signal observation means; a speaker for converting the signal from the signal processing means into a sound wave and emitting it near the operator's head at the copying machine operating position; and a signal from the signal processing means. Since the present invention is equipped with a signal processing adaptation means for predetermining processing so that the area near the operator's head at the copying machine operating position is muted, the noise level felt by the operator while operating the copying machine can be reduced, and Noise can be reduced during operator operations without installing special equipment at the operator's operating position.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a first embodiment of the present invention.

FIG. 2 is a block diagram showing a signal processing circuit of the first embodiment.

FIG. 3 is a cross-sectional view illustrating the time of digital filter coefficient determination in the first embodiment.

FIG. 4 is a diagram showing a transfer function in a second embodiment of the present invention.

FIG. 5 is a diagram showing a transfer function in the first embodiment.

[Explanation of symbols]

21 Noise source signal observation microphone 22 Vibration pickup 23 Signal processing circuit 24 Speaker 32 Signal processing adaptation means

Claims (1)

[Claims] Claims 1: Noise source signal observation means for observing sound waves or vibrations generated inside the copying machine and causing noise and converting them into electrical signals; and signal processing means for processing signals from the noise source signal observation means. and a speaker which converts the signal from the signal processing means into a sound wave and radiates it to the vicinity of the operator's head at the copying machine operating position, and a speaker which mutes the signal processing of the signal processing means near the operator's head at the copying machine operating position. 1. A copying machine with a noise canceling device, characterized in that the copying machine is equipped with a signal processing adaptation means for predetermining the signal processing so as to reduce the noise.